From 8aa64c90ddd20ec0ca8cc5fe92a6124324c51da5 Mon Sep 17 00:00:00 2001
From: Siri Hansen <siri@erlang.org>
Date: Wed, 16 May 2018 16:10:30 +0200
Subject: Use system_time instead of monotonic_time as timestamp in logger

---
 lib/kernel/src/code_server.erl      |  4 ++--
 lib/kernel/src/logger.erl           |  2 +-
 lib/kernel/src/logger_formatter.erl | 11 +++++------
 lib/kernel/src/logger_simple.erl    |  7 +++----
 4 files changed, 11 insertions(+), 13 deletions(-)

(limited to 'lib/kernel/src')

diff --git a/lib/kernel/src/code_server.erl b/lib/kernel/src/code_server.erl
index bbfa2a995d..1a7677295b 100644
--- a/lib/kernel/src/code_server.erl
+++ b/lib/kernel/src/code_server.erl
@@ -1437,7 +1437,7 @@ error_msg(Format, Args) ->
     logger ! {log,error,Format,Args,
               #{pid=>self(),
                 gl=>group_leader(),
-                time=>erlang:monotonic_time(microsecond),
+                time=>erlang:system_time(microsecond),
                 error_logger=>#{tag=>error}}},
     ok.
 
@@ -1446,7 +1446,7 @@ info_msg(Format, Args) ->
     logger ! {log,info,Format,Args,
               #{pid=>self(),
                 gl=>group_leader(),
-                time=>erlang:monotonic_time(microsecond),
+                time=>erlang:system_time(microsecond),
                 error_logger=>#{tag=>info_msg}}},
     ok.
 
diff --git a/lib/kernel/src/logger.erl b/lib/kernel/src/logger.erl
index a839f97e62..281521ae6e 100644
--- a/lib/kernel/src/logger.erl
+++ b/lib/kernel/src/logger.erl
@@ -833,7 +833,7 @@ proc_meta() ->
 
 default(pid) -> self();
 default(gl) -> group_leader();
-default(time) -> erlang:monotonic_time(microsecond).
+default(time) -> erlang:system_time(microsecond).
 
 %% Remove everything upto and including this module from the stacktrace
 filter_stacktrace(Module,[{Module,_,_,_}|_]) ->
diff --git a/lib/kernel/src/logger_formatter.erl b/lib/kernel/src/logger_formatter.erl
index 602c666cc7..a19e7bbc73 100644
--- a/lib/kernel/src/logger_formatter.erl
+++ b/lib/kernel/src/logger_formatter.erl
@@ -197,16 +197,15 @@ truncate(String,Size) ->
             String
     end.
 
-format_time(Timestamp,#{time_offset:=Offset,time_designator:=Des})
-  when is_integer(Timestamp) ->
-    SysTime = Timestamp + erlang:time_offset(microsecond),
+%% SysTime is the system time in microseconds
+format_time(SysTime,#{time_offset:=Offset,time_designator:=Des})
+  when is_integer(SysTime) ->
     calendar:system_time_to_rfc3339(SysTime,[{unit,microsecond},
                                              {offset,Offset},
                                              {time_designator,Des}]).
 
-%% Assuming this is monotonic time in microseconds
-timestamp_to_datetimemicro(Timestamp,Config) when is_integer(Timestamp) ->
-    SysTime = Timestamp + erlang:time_offset(microsecond),
+%% SysTime is the system time in microseconds
+timestamp_to_datetimemicro(SysTime,Config) when is_integer(SysTime) ->
     Micro = SysTime rem 1000000,
     Sec = SysTime div 1000000,
     UniversalTime =  erlang:posixtime_to_universaltime(Sec),
diff --git a/lib/kernel/src/logger_simple.erl b/lib/kernel/src/logger_simple.erl
index 5272455a2d..c8cdf25887 100644
--- a/lib/kernel/src/logger_simple.erl
+++ b/lib/kernel/src/logger_simple.erl
@@ -70,7 +70,7 @@ log(#{msg:=_,meta:=#{time:=_}}=Log,_Config) ->
                 do_log(
                   #{level=>error,
                     msg=>{report,{error,simple_handler_process_dead}},
-                    meta=>#{time=>erlang:monotonic_time(microsecond)}}),
+                    meta=>#{time=>erlang:system_time(microsecond)}}),
                 do_log(Log);
             _ ->
                 ?MODULE ! {log,Log}
@@ -126,7 +126,7 @@ drop_msg(0) ->
 drop_msg(N) ->
     [#{level=>info,
        msg=>{"Simple handler buffer full, dropped ~w messages",[N]},
-       meta=>#{time=>erlang:monotonic_time(microsecond)}}].
+       meta=>#{time=>erlang:system_time(microsecond)}}].
 
 %%%-----------------------------------------------------------------
 %%% Internal
@@ -141,8 +141,7 @@ do_log(#{msg:=Msg,meta:=#{time:=T}}) ->
     display_date(T),
     display(Msg).
 
-display_date(Timestamp0) when is_integer(Timestamp0) ->
-    Timestamp = Timestamp0 + erlang:time_offset(microsecond),
+display_date(Timestamp) when is_integer(Timestamp) ->
     Micro = Timestamp rem 1000000,
     Sec = Timestamp div 1000000,
     {{Y,Mo,D},{H,Mi,S}} = erlang:universaltime_to_localtime(
-- 
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